Supraventricular Tachycardia (SVT)

Transcription

1 Supraventricular Tachycardia (SVT) Daniel Frisch, MD Cardiology Division, Electrophysiology Section Thomas Jefferson University Hospital

2 Short RP Are these the Mid same RP tachycardias? Long RP

3 Outline I. Classification/Clinical II. Circuits III. Pathophysiology IV. ECG Diagnosis

4 SVT Narrow QRS Wide QRS Irregular QRS Regular QRS Aberration Pre-excitation Atrial Fibrillation Atrial Flutter Atrial Tachycardia AV Nodal Reentrant Tachycardia AV Reentrant Tachycardia

5 SVT Narrow QRS Wide QRS Irregular QRS Regular QRS Aberration Pre-excitation Atrial Fibrillation Atrial Flutter Atrial Tachycardia AV Nodal Reentrant Tachycardia AV Reentrant Tachycardia

6 Epidemiology of SVT AF and AFL are the most common arrhythmias affecting >2 million people in the US The most common SVT is AVNRT (60%), followed by AVRT (30%), and AT (10%) AVNRT is more common in women (70%) Mean age of onset 32y AVRT is more common in men Mean age of onset 23y AT is more common with older age and structural heart disease Orejarena, LA. PSVT. JACC 31: , 1998

7 Clinical History in SVT Symptoms Palpitations ( irregular or skipped beats) Exertional fatigue/dyspnea Chest discomfort Near-syncope (rarely syncope) Historical Features Triggers Abruptness of onset and termination Common in AVRT and AVNRT Frequency of episodes Incessant is often AT Ability to stop symptoms Common in AVRT and AVNRT SVT Sinus tachycardia AT AVNRT AVRT Possible Effect of CSM Gradual, temporary slowing of HR AV block Cessation Cessation Adapted from Wellens ECG in Emergency Decision Making 2006

8 Circuits

9 Diagramming SVT P P P P P P P P P P P P P P P 1 beat A 1 beat Next beat AVN His V

10 Sinus Rhythm Atrium AVN HPS Ventricle

11 Atrial Tachycardia Atrium AVN HPS Ventricle

12 Typical AVNRT Atrium AVN HPS Ventricle Retrograde fast pathway Antegrade slow pathway Indicates reentrant mechanism

13 Orthodromic AVRT Atrium AVN HPS Ventricle The curved lines depict extra-hisian depolarization of the atrium due to conduction up an accessory pathway (AP) VA intervals are longer than VA intervals in AVNRT because of sequential activation Retrograde AP conduction Indicates reentrant mechanism

14 RP Intervals in AVNRT, AVRT, and AT AVNRT AVRT AT Atrium AVN HPS Ventricle RP RP RP Retrograde fast pathway Antegrade slow pathway Retrograde AP conduction AT Source Indicates reentry *RP interval is shorter in AVNRT vs. AVRT and AT because of parallel rather than sequential activation of the atria and ventricles. *Cycle length variation in AT is shown intentionally to demonstrate that A- A changes precede H-H or V-V changes.

15 Pathophysiology Courtesy of M. Josephson

16 AVNRT, AVRT, or AT? Courtesy of M. Josephson

17 AVNRT, AVRT, or AT? 1. AVNRT 2. AVRT 3. AT 33% 33% 33% 1 2 3

18 Courtesy of M. Josephson

19 Initiation of Typical AVNRT with an APD Atrium AVN HPS Ventricle An APD blocks in the fast pathway, conducts antegrade over the slow pathway, and then retrograde over the fast pathway Fast pathway Slow pathway Atrial premature depolarization Block Indicates reentrant mechanism VA

20 Initiation Trend review Termination

21 48 M with palpitations Typical or Atypical AVNRT? Baseline Typical AVNRT The P wave and QRS must be simultaneous (because you cannot see the P wave)

22 Simultaneous QRS complexes and P waves QRS complex P wave

23 How Does the Termination of this SVT Help Determine the Mechanism? Termination with a P wave

24 Termination of AVNRT vs. AT AVNRT AT Atrium AVN HPS Ventricle Retrograde fast pathway Antegrade slow pathway AT Source Sinus beat The last beat of AVNRT would be expected to depolarize both A & V The last beat of AT would be expected to depolarize only the V

25 AVNRT, AVRT, or AT? BPM BPM Courtesy of M. Josephson

26 AVNRT, AVRT, or AT? 1) AVNRT 2) AVRT 3) AT 33% 33% 33% 1) 2) 3)

27 AVRT AVNRT Coumel s Law If Right AP and RBBB: Then VA and TCL increase If Left AP and LBBB Then VA and TCL increase Courtesy of M. Josephson

28 AVRT with Left-Sided AP and LBBB Atrium AVN HPS Ventricle When an a bundle branch block develops ipsilateral to the site of an AP (in this case a left bundle [LB] branch block in the presence of a left-sided AP) the VA interval increases with or without an increase in the SVT rate

29 Orthodromic AVRT with Ipsilateral BBB Atrium AVN HPS Ventricle VA VA When an a bundle branch block develops ipsilateral to the site of an AP (in this case a left bundle [LB] branch block in the presence of a left-sided AP) the VA interval increases with or without an increase in the SVT rate

30 42 M with a history of palpitations since his teens AVNRT, AVRT, or AT? Δ Δ Δ Δ Note the Δ wave! An accessory pathway is the likely involved the SVT (AVRT)

31 AVNRT, AVRT, or AT? 1) AVNRT 2) AVRT 3) AT 33% 33% 33% 1) 2) 3)

32 QRS Alternans (a feature of AVRT)

33 AVNRT, AVRT, or AT?

34 AVNRT, AVRT, or AT? 1) AVNRT 2) AVRT 3) AT 33% 33% 33% 1) 2) 3)

35 LS RS LI LA RI RA Right Lateral view showing Posteroinferior RA septal AT

36 ATs Tend to cluster Kistler PM et al. P-Wave Morphology in Focal Atrial Tachycardia. JACC 2006;48:

37 ECG Diagnosis: tbnid=atklgnqc5w3-zm:&tbnh=87&tbnw=133&hl=en&start=3&prev=/images%3fq%3dnormal%2bekg%26svnum%3d10%26hl%3den%26lr%3d

38 Surface ECG Analysis of SVT All cases: 1. Identify the P wave 2. Determine the P wave axis and morphology 3. Determine the P wave relationship to the QRS 4. Determine the RP and PR intervals 5. Determine the presence/absence of QRS alternans Selected cases: 6. Note the influence of VPDs or BBB on the tachycardia 7. Note the initiation and termination of the tachycardia 8. Note the consequence of vagal maneuvers on the SVT

39 ECG Characteristics of SVT ECG Sign AVNRT AVRT AT AV Block Rare Excluded if present Possible QRS Alternans Rare Common Rare P wave location Within QRS Between QRSs. Fixed RP Between QRSs. RP varies P wave polarity Always (-) in II, III, avf Often (-) in II, III, avf Often (+) in II, III, avf P wave width Narrow Variable Variable Aberrancy Rare Common Uncommon Adapted from Wellens ECG in Emergency Decision Making 2006

40 ECG Diagnosis: Tips 1.Enhance the view Gain it up (2X or more) Speed it up (paper speed mm/sec) 2.Remember CSM 3.Compare to baseline

41 71M with Fatigue What is the Rhythm?

42 Carotid Sinus Massage (Left) Flutter Waves

43 Post Cardioversion Initial

44 Conclusions Pre-Interpretation Interpretation 1. Recall the pathophysiology of the different SVTs 2. Use all available information Epidemiology Response to Rx (adenosine) 3. Enhance the view on ECG Gain it up (2X or more) Speed it up (paper speed mm/sec) 4. Remember CSM 5. Compare to baseline Look for pre-excitation (WPW) 1. Find zones of transition Initiation (APD with long PR?), termination (P wave?) 2. Look for perturbations SVT with BBB, initiation and/or termination with VPD, change in RP interval or change in SVT rate with BBB should raise suspicion for AP 3. Persistence of SVT with AV block excludes AVRT 4. (+) P waves II,III,F suggest AT 5. QRS alternans suggests AVRT

45 Selected References Josephson ME and Wellens HJ. Differential diagnosis of supraventricular tachycardia. Cardiol Clin Aug;8(3): Wellens HJJ, Conover MB. The ECG in Emergency Decision Making. Ed. 2. Philadelphia, Saunders, 2005.

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47 Supraventricular Tachycardia (SVT) Daniel Frisch, MD Cardiology Division, Electrophysiology Section Thomas Jefferson University Hospital